1. Field of the Invention
The present invention relates to a heat pump system, and more particularly, to a heat pump system that is capable of removing frost formed on an outdoor heat exchanger while maintaining a heating operation.
2. Description of the Related Art
In general, a heat pump is a device for heating or cooling an indoor space by sequentially performing operations of compressing, condensing, expanding, and evaporating a refrigerant.
In the conventional heat pump, when a heating operation is performed in winter, an outdoor temperature is low such that frost is formed on the surface of an outdoor heat exchanger. In order to remove frost formed on the surface of the outdoor heat exchanger, the heating operation stops being performed for a moment, and a defrosting operation is performed for a predetermined amount of time. In the defrosting operation, a 4way valve is switched to change a flow of the refrigerant like in a cooling operation. A high-temperature refrigerant vapor discharged from the compressor flows into the outdoor heat exchanger, is used to melt and remove frost formed on the outdoor heat exchanger.
However, when the heating operation is temporarily switched to a cooling operation so as to perform the defrosting operation in winter, cold wind is blown indoors, which gives an unpleasant feeling to a user.
When an additional defrosting device is installed so as to perform the defrosting operation, a structure of the heat pump is complicated, and the size of the outdoor heat exchanger is increased.
Korean Patent Publication No. 2003-0044452 discloses a defrosting device for a heat pump type air conditioner.